DOGS · Condition guide
Mast cell tumours in dogs: real veterinary cases
Mast cell tumours are the most common skin cancer in dogs. They can look like almost anything — a benign-seeming lump, a raised pink nodule, a hairless plaque — which is why fine-needle aspiration is so important for every new skin mass. A classic clue is that the lump waxes and wanes in size as the mast cells release histamine.
Outcome depends heavily on tumour grade. Low- and intermediate-grade tumours that are completely excised often need nothing further; high-grade or metastatic tumours need chemotherapy or targeted drugs like toceranib (Palladia). Certain breeds — Boxers, Bulldogs, Pugs, Boston Terriers, Labradors, Golden Retrievers — are especially predisposed.
What vets typically check for
- Fine-needle aspirate and cytology — diagnostic in most cases without surgery.
- Surgical removal with wide margins (2-3 cm lateral, one fascial plane deep where possible).
- Histopathology to assign Patnaik grade (I/II/III) and Kiupel grade (low/high).
- Staging: regional lymph node aspirate; abdominal ultrasound for high-grade or stage II+ tumours.
- Adjuvant: vinblastine + prednisone chemotherapy or toceranib (Palladia) in high-grade cases.
Not a replacement for veterinary care. Use this to walk into the conversation prepared, not to self-diagnose.
Real cases from the veterinary literature
Peer-reviewed reports our semantic search surfaces for Mast cell tumour (MCT). Click into any case for the full abstract — or run a personalised search with your pet's exact details.
- The use of a bipolar single-needle electrode for electrochemotherapy combined with gene electrotransfer of IL-12 in a mast cell tumor on the nasal planum of a dog: case report.
Frontiers in veterinary science · 2026
A dog with a mast cell tumor (a type of skin cancer) on its nose was treated using a special method that combined electrochemotherapy and gene therapy. The treatment involved injecting a chemotherapy drug and a gene that helps fight cancer directly into the tumor, followed by applying electric pulses with a single-needle electrode. This approach not only reduced the tumor's blo
- Clinical, pathological and prognostic features of surgically excised cutaneous and subcutaneous digital and distal limb mast cell tumours in dogs.
The Journal of small animal practice · 2026 · United States
A group of 115 dogs with mast cell tumors on their paws or lower legs underwent surgery to remove these growths. After surgery, about 38% of the dogs experienced complications, like infections or issues with the surgical site healing. The chance of the tumor coming back was higher in dogs with high-grade tumors or those that weren't completely removed. Dogs that had their tumor
- Atypical scattergram of a canine peripheral blood sample on ProCyte Dx
Veterinary Record Case Reports · 2026 · Italy
A 9-year-old spayed female fox terrier was brought to the vet after experiencing two episodes of partial seizures. Blood tests showed an unusual pattern that suggested the presence of mast cells, which led to further examination and a diagnosis of a mast cell tumor in her spleen. This type of tumor can be serious, but with the right treatment, the dog can receive appropriate ca
- Eyebrow and Upper Eyelid Reconstruction With a Double Rhomboid Flap in a Dog.
Veterinary ophthalmology · 2026 · United States
A 2-year-old male Golden Retriever had a large tumor on his eyebrow and upper eyelid, which was diagnosed as a benign skin tumor. After the tumor was surgically removed, the vet used a special technique called a double rhomboid flap to reconstruct the area. Three months later, the dog showed no signs of tumor regrowth, and any temporary eyelid issues resolved completely. The su
- Multimodal treatment of canine lower eyelid mast cell tumours: lip-to-lid reconstruction and sentinel lymph node mapping in two cases.
BMC veterinary research · 2026
A 7-year-old mixed breed dog was brought in with a firm nodule on the lower eyelid, which was diagnosed as a mast cell tumor, a common skin tumor in dogs. The veterinarian performed surgery using a lip-to-lid reconstruction technique to remove the tumor while preserving the eyelid's function and appearance. They also mapped the sentinel lymph node to check for any spread of the
- Expanding access to cancer care: 10% fluorescein sodium is a practical, low-cost method for intraoperative sentinel lymph node mapping in dogs.
Journal of the American Veterinary Medical Association · 2026
A group of dogs with skin tumors underwent a new procedure using a special dye called fluorescein sodium to help identify cancerous lymph nodes during surgery. In this small study, the dye successfully highlighted lymphatic pathways in five out of six dogs, allowing veterinarians to locate sentinel lymph nodes (the first nodes that cancer might spread to). The procedure was saf
Frequently asked questions
- Should I aspirate every lump?
- Yes — fine-needle aspirate is cheap, fast, and the only reliable way to identify a mast cell tumour before surgery. "Watch and wait" is risky, because MCTs that get bigger before they're removed need a larger excision and have worse outcomes.
- Why does the lump shrink and swell?
- Mast cells release histamine when they're disturbed, causing local swelling and redness ("Darier's sign"). This is why pressing or rubbing a lump that grows and then shrinks an hour later is so characteristic.
- What's the prognosis?
- Low-grade tumours completely excised — excellent, often considered cured. High-grade tumours have a guarded prognosis but modern chemotherapy and targeted drugs have markedly improved outcomes in the last decade.